This project has concentrated on the functional roles of proteins which are rapidly transported by axons in the nervous system by first examining the species of rapidly transported proteins in functionally distinct systems (sensory, motor and sympathetic). The results show that a number of distinct classes of proteins heavily labelled with methionine and of the same approximate molecular weights are transported in the functionally different systems. The degree of coincidence of rapidly transported proteins has been further enhanced by separating the methionine-labelled proteins on SDS polyacrylamide slab gels and examining autoradiographs of the separated proteins. These rapidly transported species thus appear to be involved in some processes basic to all nerve cells rather than peculiar to any one functional type of cell. Study of the functions of the rapidly transported species has begun with 1) investigation of Ca ions transport in the same systems and search for a rapidly transported protein with high affinity for Ca ions and 2) experiments on the distribution of autoradiographic grains in the spinal cord following transport of labelled proteins in the sensory system.